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Planetary News: SMART-1 (2006)

SMART-1 Mission Goes Out With a Bang

by Melanie Melton Knocke
September 3, 2006

By now, most if not all of the dust has settled from SMART-1's intentional impact with the lunar surface.

The small spacecraft, representing Europe's first lunar mission, slammed into the Moon at 5:42:21 UT on September 3 (10:42:21 pm PDT, September 2), within a second of the predicted impact time.

SMART-1 plowed into the ground traveling approximately 2 kilometers per second (1.2 miles per second).

While the small telescopes set up at Planetary Society headquarters in Pasadena, as well as telescopes at Griffith Observatory in Los Angeles, reported seeing nothing unusual at the time of impact, a brief explosion was captured by infrared cameras attached to the French Canadian Hawaiian Telescope high atop Mauna Kea in Hawaii.

Lunar Impact as Seen from Earth
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Lunar Impact as Seen from Earth
The 3.6-meter optical/infrared Canada-France-Hawaii Telescope (CFHT) in Hawaii captured this impressive sequence of SMART-1 impact images showing before, during, and after the impact. The impact flash may have been caused by the thermal emission from the impact itself or by the release of spacecraft volatiles, such as the small amount of hydrazine fuel remaining on board. Credit: Canada-France-Hawaii Telescope Corporation

More images are at ESA's SMART-1 website.

It will take several days for SMART-1's scientists to collect and analyze all the images and data gathered by observers worldwide. Even still, the mission can be called an unqualified success.

The last few hours of SMART-1's life were not without some drama. The day before impact, engineers had determined that the mile-high rim of the crater Clausius lay directly along SMART-1's flight path. Left to its own, the spacecraft would have slammed into the edge of Clausius an orbit early.

To assure the best possible observing opportunities here on Earth, engineers decided to use the spacecraft's thrusters to slightly raise SMART-1's orbit one last time. This maneuver would allow the spacecraft to clear the crater rim, yet still impact in the Lake of Excellence within a couple of minutes of the originally predicted time.

The Moon's Horizon
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The Moon's Horizon
SMART-1's AMIE camera captured this oblique view of the lunar surface on September 2, 2006 during the last few orbits prior to Moon impact. Credit: ESA / SPACE-X (Space Exploration Institute)

However, just before the maneuver was to take place, the spacecraft went into safe mode, indicating that the onboard computer had sensed a problem and placed the spacecraft into a predetermined "safe" orientation.

After a nail-biting five hours, controllers on Earth were able to re-establish contact, just in time for SMART-1 to fire its thrusters and complete the maneuver.

With SMART-1's mission at an end, its legacy will continue in the form of the many new technologies it introduced. Instruments tested onboard SMART-1 are scheduled to fly onboard Chandrayaan 1, India's first lunar mission in 2007-8. SMART-1's ion engine is the basis for the European Space Agency's BepiColombo mission to Mercury in 2013.

Congratulations to the engineers and scientists at the European Space Agency for the success of SMART-1. Thanks for the ride!